This invention relates generally as indicated to an anti-rotation device for contracting rod ring seals and more particularly to a device for preventing relative rotation between the inner and outer rings of a contracting rod ring seal or other such multi-ring circumferential seal to prevent the gaps in the rings from aligning themselves.
A typical contracting rod ring seal consists of a step cut inner ring and a straight cut outer ring concentrically disposed about the inner ring. Such a seal is normally used to seal in one direction against high pressure fluid or gas leakage around a rod protruding from a pressure vessel. In certain instances, the cuts or gaps in the inner and outer rings will align themselves due to combinations of pressure cycling, rod motion and/or vibration and the like. With the gaps aligned, the seal develops excessive leakage making it unsuitable for its intended function.
Heretofore, in some applications it has been possible to maintain the ring gaps out of alignment with each other by providing a pin between the rings or in the outer ring protruding into the gap in the inner ring. However, in other applications requiring smaller, thinner rings the drilling of holes and installing of pins can cause distortion of the rings and consequent leakage.
It is also known to provide a stress transmitting band in opposed grooves in the concentric rings to prevent the rings from rotating relative to each other. Such relative rotation of the rings is prevented by axially and circumferentially spaced detents on the band which project into the gaps in the respective rings. However, the forming of such grooves in the rings for receipt of the band has similar drawbacks to the drilling of holes and installing of pins especially in applications requiring smaller, thin rings.